Primary spontaneous pneumothorax is defined as the presence of air in the pleural space with no precipitating cause and is four times less likely to occur in women than in men1,2. Common causes for spontaneous pneumothorax in females include: interstitial pneumonia, primary lung cancer and lung metastasis, and asthma3.  An uncommon cause for secondary spontaneous pneumothorax is catamenial pneumothorax, which is associated with thoracic endometriosis. The word “catamenial” is derived from the greek word “katamenios” meaning monthly recurrence.4 Catamenial pneumothorax refers to recurrent spontaneous pneumothorax during menstruation in the absence of concomitant respiratory disease5.

Dermatomyositis is an autoimmune disease that is considered a subset of idiopathic inflammatory myopathy. It is characterized by a skin rash with progressive muscle weakness. Pneumomediastinum is a rapidly progressive complication of dermatomyositis, which is hypothesized to be a result of ruptured subpleural cysts, pulmonary vasculopathy, and steroid-mediated weakening of alveolar walls. This complication is associated with a high mortality rate of 30%. Hence, it should be rapidly investigated and treated when there is a high clinical suspicion. In this article, we report a rare case of patient with dermatomyositis (DM) who developed pneumomediastinum and discussed a literature review of this occurrence.